Electron vacuum tube employing orbiting electrons



April 5, 1966 R. G. HERB ETAL 3,244,990

ELECTRON VACUUM TUBE EMPLOYING ORBITING ELECTRONS Filed Feb. 26, 1965 3 Sheets-Sheet 1 rlllllllllllllll IV fiqYMolva 6. Hana one PAULY THEOD INVENTORS Arrvs.

April 5, 1966 R. G. HERB ETAL 3,244,990

ELECTRON VACUUM TUBE EMPLOYING ORBITING ELECTRONS Filed Feb. 26, 1963 5 Sheets-Sheet 2 \00 Q EW no 5 l I i l i I i VIII/IA l lllllll H g I Raw/mono 6. HERB THEODORE PAULY INVENTORS BY 5 @m. 7% 8% April 1966 R. G. HERB ETAL 3,244,990

ELECTRON VACUUM TUBE EMPLOYING ORBITING ELECTRONS Filed Feb. 26, 1965 5 Sheets-Sheet 5 RAYMOND G. Hsna 7115mm: 5 PA ULY INVENTORS United States Patent Ofiice 3,244,990 ELECTRON VACUUM TUBE EMPLOYING ORBITING ELECTRONS Raymond G. Herb and Theodore E. Pauly, Madison, Wis., assignors to Wisconsin Alumni Research Foundation, Madison, Wis., a corporation of Wisconsin Filed Feb. 26, 1963, Ser. No. 261,104 19 Claims. (Cl. 328-252) Certain aspects of the subject matter disclosed in this application are disclosed and claimed in our copending application, Serial No. 332,190, filed December 20, 1963, which is a continuation-in-part of the present application.

This invention relates to electron orbiting devices and pertains particularly to devices which have important applications to ion gauges, electrometer tubes, amplifying devices and ion-getter vacuum pumps.

One object of the present invention is to provide a new and improved electronic device which is so arranged that the mean free path of the electrons may be much longer than the overall size of the device, so that the probability that any electron will ionize a gas molecule in the device is greatly increased, the device thereby being adapted to serve as a highly efficient ion gauge, or as an ionizing device for an ion-getter vacuum pump.

A further object is to provide a new and improved electronic device of the foregoing character in which the mean free path of the electrons is increased by causing the electrons to travel in spiral paths or orbits, around one of the electrodes of the device, without utilizing any magnetic field.

A still further object is to provide a new and improved electron orbiting device of the foregoing character in which electrons are caused to move in spiral orbits in an electric field between an outer cylindrical electrode and an axial electrode in the form of a wire or cylinder received within the outer electrode.

. Another object is to provide such a new and improved electron orbiting device in which electrons are injected or introduced into the space between the inner and outer electrodes with a substantial angular momentum so that electrons will travel in spiral orbits around the inner electrode.

A further object is to provide such a new and improved electron orbiting device in which the electrons may be injected by a heated filament disposed between the inner and outer electrodes and generally parallel to the inner electrode.

Another object is to provide such a new and improved electron orbiting device in which the proportion of electrons injected with high angular momentum is increased by providing an auxiliary electrode or shield to cooperate.

with the filament.

Another object is to provide a new and improved electron orbiting device of the foregoing character which may include one or more reflector electrodes at or near either or both ends of the outer electrode for reflecting the spiraling electrons.

A further object is to provide a new and improved electron orbiting device of the foregoing character having a light shield between the filament and the outer electrode to avoid photoelectric emission of electrons from the outer electrode due to the light produced by the filament.

Another object is to provide a new and improved electron orbiting device of the foregoing character and hav ing a collector electrode and a control electrode disposed between the filament and the collector electrode so that the discharge device may serve as an electrometer tube or an amplifying device.

, A further object is to provide electron orbiting devices of the foregoing character which consume very little power and are extremely eflicient.

Another object is to provide a new and improved electron orbitin-g device which will serve as an extremely sensitive ion gauge which generates a minimum of heat and generally causes very little disturbance in the vacuum system in which the ion gauge is employed.

A further object is to provide a new and improved electron orbiting device which will serve as an electrometer tube'or amplifying device having unusually high gain.

Various other objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a diagrammatic view, partly in perspective and partly in section, showing an electron orbiting device to be described as an illustrative embodiment of the present invention, such device being arranged to serve as an ion gauge or as an ionizing device for an ion-getter vacuum pump.

FIG. 2 is a central longitudinal sectional View taken through the device of FIG. 1.

FIG. 3 is an end view taken generally as indicated by the line 33 in FIG. 2.

FIG. 4 is a cross-sectional view, taken generally along the line 44 in FIG. 3.

FIG. 5 is a fragmentary enlarged elevational view illustrating the electron emitting filament and the associated shield wire as employed in the device of FIG. 1.

FIG. 6 is a view similar to FIG. 5, but illustrating a modified arrangement of the filament and shield wire.

FIG. 7 is a view similar to FIG. 2 but showing a modified construction having an additional reflector electrode and also the modified filament of FIG. 6.

FIG. 8 is a fragmentary view corresponding to the upper portion of FIG. 7 but illustrating a modified reflector electrode.

FIG. 9 is a diagrammatic cross-sectional view taken generally along the line 9-9 in FIG. 7, and showing possible orbits which may be traversed by some of the electrons.

FIG. 10 is a cross-sectional view, similar to FIG. 4, but illustrating a modified construction in which an electron gun provides the source of the electrons injected into the orbiting device.

FIG. 1'1 is a longitudinal sectional view showing a modified electron discharge device similar to that of FIG. 7, but including a light shield around the filament.

FIG. 12 is a longitudinal sectional view of a modified electron orbiting device provided with a collector electrode and a control electrode so as to serve as an electrometer tube or amplifying device.

FIG. 13 is a longitudinal sectional view showing a modified amplifying device adapted to be used at higher signal frequencies than the device of FIG. 12.

As already indicated, FIG. 1 illustrates an electron orbiting device 20 which is well adapted for use as an ion gauge in a vacuum chamber or system. Various ion gauges are already known for the purpose of giving an indication of the number of gas molecules in a vacuum system. In such ion gauges, electrons are caused to travel between the electrodes in the evacuated space. Some of the electrons will collide with gas molecules so as to ionize such molecules. The ionized gas molecules are then attracted to an ion collector electrode. The ion current is a measure of the concentration of the gas molecules in the vacuum system.

The electron orbiting device 20 of FIG. 1 has the important advantage that the electrons are caused to traverse spiral paths or orbits, in moving between the cathode and anode electrodes, so that the mean free path of the electrons is greatly lengthened. In this way, there is a much greater probability that each electron will Patented Apr. 5, 1966- ionize a gas molecule before passing to the anode. Thus, the electrons are utilized with greatly increased efiiciency.

In the electron orbiting device 20 of FIG. 1, the electrons are caused to spiral in an electric field between an outer cylindrical electrode 22 and an inner or axial electrode 24. It will be seen that the outer electrode 22 has a cylindrical inner surface 26 which serves as the boundary of a cylindrical space 28 through which the electrons move. The illustrated outer electrode 22 is in the form of a thin-walled cylindrical metal tube, but it will be understood that the shape of the outside of the electrode 22 is of no particular concern and may be changed as may be desired or convenient.

The inner electrode 24 extends along the axis of the cylindrical surface 26 and is received within the outer electrode 22. The inner electrode 24 has a cylindrical outer surface 30. In this case, the inner electrode 24 is in the form of a cylindrical metal wire or rod, but it will be understood that the inner electrode may be hollow and tubular in form without affecting the operation of the electron orbiting device.

An electric field is produced in the space between the outer and inner electrodes 22 and 24 by impressing a voltage between such electrodes. Normally, the inner electrode 24 is positively charged so as to attract electrons. The outer electrode 22 is negatively charged so as to attract positively ionized gas molecules. The operating voltage may be derived from any suitable source of direct potential, such as a battery 32. It will be seen that a lead 34 is connected between the positive terminal of the battery 32 and the axial electrode 24. The negative terminal of the battery 32 may be grounded. In this case, a meter 36 for measuring the ion current is connected between the outer electrode 22 and ground. Thus, the negative terminal of the battery 32 is connected to the outer electrode 22 by way of the ground connections and the meter 36.

Electrons are injected into the space 28 between the outer and inner electrodes 22 and 24 in such a manner that some or all of the electrons will have suflicient angular momentum to travel in orbital paths around the positively charged central electrode 24. In this case, the electrons are enabled to traverse extremely long paths before finally being captured by the positively charged electrode or anode 24. Most of the orbiting electrons will travel in spiral paths which will not necessarily be circular.

Various electron injecting devices may be employed to introduce the electrons into the space between the concentric cylindrical electrodes 22 and 24. FIG. 1 illustrates a particularly simple yet effective electron injecting device 38 comprising a small narrow hairpin-shaped filament 40 disposed between the electrodes 22 and 24, near one end of the outer electrode 22. The illustrated filament 40 has parallel legs 42 and 44 which extend substantially parallel to the axial electrode 24. The axes of the legs 42 and 44 are in a single radial plane which also includes the axis of the central electrode 24. The filament 40 may be in the form of a fine wire made of tungsten or other suitable metal. An electric current may be passed through the filament 40 to heat the filament so that it will emit electrons. To supply the filament 40 with current, the ends of the filament are connected to heavier lead-in wires 46 and 48 which also serve as supports for the filament. The lead-in wires 46 and 48 may be brought into the space 28 through openings in aninsulating rod or member 50 which may be made of ceramic material or the like.

Current for heating the filament 40 may be derived from any suitable source, such as a low voltage secondary winding 52 of a transformer 54. The primary winding 56 of the transformer 54 may be connected to an ordinary commercial source of alternating current at 110 volts and 60 cycles, or any other suitable voltage and frequency.

The filament 40 is preferably given a positive bias relative to the outer electrode 22. In this way, the electrons emitted from the filament 40 will be repelled from the outer electrode 22. Such biasing voltage may be derived from any suitable source, such as a battery 58. In this case, a variable potentiometer 60 is connected across the battery. The slider 62 of the potentiometer is connected to the center tap 64 of the secondary winding 52 so that the biasing voltage on the filament may be varied by adjusting the potentiometer 60-.

Most of the electrons will be emitted from the filament 40 in directions other than a radially inward direction and thus will acquire substantial angular momentum, due to the electric field around the filament. Although the emitted electrons will be attracted by the positively charged axial electrode 24, many of the electrons will avoid immediate capture by the axialelectrode by traveling in spiral paths or orbits around the axial electrode. The electrons may avoid capture for many revolutions so that the mean free path of the electrons may be many times the greatest over-all dimension of the electron orbiting device.

A shield electrode 66 may be provided between the electron injecting filament 40 and the central electrode 24 to prevent direct radial movement of electrons between the filament and the positively charged central electrode. As shown, the shield electrode 66 is in the form of a rod or wire which is parallel to the central rod 24 and the filament wires 42 and 44. The axis of the illustrated shield wire 66 is in the same radial plane as the axes of the legs 42 and 44 of the filament 40. The shield wire 66 may be mounted on and connected to the inner lead wire 46. Thus, the shield wire 66 is at substantially the same biasing voltage as the filament 40. The electric field around the filament 40 is modified by the shield wire 66 so that greater angular momentum may be imparted to the electrons emitted by the filament. It has been found, however, that the shield wire 66 is not strictly necessary and that electrons can be caused to orbit in spiral paths around the central electrode 24, even if the shield wire is omitted entirely.

In this case, the electron orbiting device 20 is also provided with a reflector plate or electrode 68 which is opposite one end of the cylindrical outer electrode 26. The reflector electrode 68 is circular in shape and corresponds generally in diameter to the cylindrical electrode 22. As shown, the reflector electrode 68 is in the form of a that circular disk disposed perpendicular -to the axis of the cylindrical electrode 22. The central electrode 24 passes through a central opening 70 in the reflector electrode 68. Another opening 72 is formed in the reflector electrode 68 to pass the lead-in wires 46 and 48 and the insulating support 50 for the filament 40.

The reflector electrode 68 is preferably given a negative bias, relative to the outer electrode 26 so as to repel the electrons and cause them to spiral around the central electrode 24. Such bias may be derived from any suitable source, such as a battery 74. A potentiometer 76 may be connected across the battery 74. The slider 78 of the potentiometer is connected to the reflector electrode 68 by a lead 80. The positive terminal of the battery 74 is grounded. By adjusting the potentiometer 76, the bias voltage on the r eflector electrode 68 may be varied.

It will be evident from FIGQS that the shield wire 66 is offset in a radially inward direction from the lead-in Wire 46. FIG. 6 illustrates a modified electron injector 84 comprising a shield wire 86 which constitutes a linear extension of the lead-in wire 46. The construction of FIG. 6 employs a modified electron emitting filament 88 which is L-shaped. The filament 88 has an elongated leg 90 extending parallel to the shield wire 86. One end of the leg 90 is connected to the end of the lead-in wire 48. A shorter leg 92 extends between the other end of the leg 90 and the shield wire 86. Here again, the filamen-t '88 may be made of fine tungsten wire.

The electron orbiting device 20 provides a highly efficient ion gauge. With this gauge, electron mean free paths greater than 1,000 centimeters have been achieved, even though the maximum dimension of the gauge was only a few centimeters. Moreover, the gauge has yielded a positive ion current five times greater than an available ion gauge of the Bayard-Alpert type, even though the power consumption and electron emission of the present gauge was much less than that of the available gauge.

The electron orbiting device 20 may also serve as an eflicient ionizing device for an ion-getter vacuum pump, in which the gas ions produced by the ionizing device are absorbed by a getter material. Normally, the getter is supplied by a getter sputtering device.

FIG. 7 illustrates a modified electron orbiting device 100 which for the most part is the same as the orbiting device 20 of FIG. 1. Corresponding components shown in FIG. 7 are given the same reference characters as in FIG. 1. Only the differences between electron orbiting devices 20 and 100 need be described in detail.

It will be seen that the orbiting device 100 employs the modified electron injector 84 of FIG. 6. The shield wire 86 is disposed between the filament 88 and the axial electrode 24. The axis of the central electrode 24, the shield wire 86 and the filament 88 are in substantially the same plane.

Moreover, the electron orbiting device 100 is provided with an additional reflector electrode 102 which is similar to the electrode 68 but is disposed opposite the other end of the outer cylindrical electrode 22. The electrode 102 is in the form of a flat circular disk having an opening 104 therein through which the central electrode 24 extends. The reflector electrode is preferably given a small negative bias voltage relative to the outer electrode 22. Such bias voltage may be derived from any suitable source, such as a battery 106 having its positive terminal grounded. A'potentiometer 108 is connected across the battery 106. The slider 110 of the potentiometer may be connected to the electrode 102.

The electrode 102 has the efiect of reflecting the spiraling electrons so that they tend to spiral in the opposite axial direction along the central electrode 24. On the other hand, the end of the outer electrode 22 of FIG. 1 is left open. It will be understood that the extra reflector electrode 102 is not strictly necessary. Long mean free paths have been obtained with the open-ended construction of FIG. 1. Like the device 20 of FIG. 1, the electron discharge device 100 of FIG. 7 is well adapted for use as an ion gauge to measure the vacuum in a vacuum system or chamber.

FIG. 8 illustrates another modified electron orbiting device 120 which is the same as the device 100 of FIG. 7 except that the electrode 102 is replaced with a reflector electrode 122 having a much larger central opening 124 therein, so that the electrode 122 is in the form of a flat ring. it has been found that the electrode construction of FIG. 8 usually results in longer mean free paths than the construction of FIG. 7.

In the electron devices of FIGS. 1-8, the electrons travel in spiral orbits around the central electrode 24. However, the orbits are not necessarily circular and in most cases will probably be noncircular. FIG. 9 indicates one type of noncircular orbit which may be .traversed by some of the electrons. It will be seen that the electrons pass close to the central electrode 24 and then travel outwardly, close to the outer electrode 22 before again turning inwardly. Orbits of this type and other noncircular orbits are usually more advantageous than circular orbits because the electron may travel through several revolutions before coming close to the electron injecting filament. A few of the electrons may be recaptured by the filament. Such recapture shortens the mean free path of the electrons. Moreover, the electric field around the filament disturbs the orbits of the electrons. Some of the orbits may be improved, but other orbits will be modified so that the electrons will pass more quickly to the central electrode. Thus, the disturbing effect of the filament generally tends to shorten the mean free path of the electrons. As the electrons spiral away from the filament, the disturbing eflect of the filament is diminished.

A mathematical analysis of the movementof electrons between the inner and outer cylindrical electrodes will provide guides as to the location of the filament and the bias to be applied to the filament. In view of the cylindrical configuration of the inner and outer electrodes,- the potential at any radius p is given by the following equation:

In this formula, i is the potential at the radius p; V is the voltage between the inner and outer cylinders; R is the radius of the outer cylinder; and r is the radius of the inner cylinder.

The electric field E between the cylinders is given by the following equation:

=Ee= R p in p Equation 4 may be solved for the kinetic energy,.giving the following equation:

This formula indicates that the kinetic energy for stability in a circular orbit is independent of'the radius p. If an electron from the filament is to have a circular orbit of the radius f, the filament must be located at such radius. In view of this fact, Equations 3 and 5 may be combined to give the following equation:

el)V

jjw w) (6) The potential given by Equation 1 may be substituted in Equation 6 to give the following equation:

6V eV In This equation may advantageously be simplified by multiplying both side by to obtain the following equation:

b In pr/R b 1n pr/R FIG. 10 comprises a diagrammatic illustration of another modified electron orbiting device 130 in which the electrons are injected into the space 28 between the outer and inner electrodes 22 and 24 by an electron gun 132 which gives the electrons sufficient angular momentum so that they spiral around the central electrode 24. The electron gun 132 may be either inside or outside the vacuum chamber in which the electrodes 22 and 24 are situated. Electron guns are well known so that it will not be necessary to describe the construction of any particular electron gun. As shown in FIG. 10, the electron gun 132 propels the electrons into the space 28 through anopening 134 in the outer cylindrical electrode 22. However, it will be understood that such an opening is not strictly necessary inasmuch as the electron gun may be aimed so as to propel the electrons into the space 28 through the open end of the cylindrical electrode 22.

FIG. 11 illustrates another modified electron orbiting device 140 which employs the same electron injector 84 as illustrated in FIG. 6. The orbiting device 140 has an outer electrode 144 with an internal cylindrical surface 146. An axial cylindrical rod or wire 148 forms the inner electrode. Thus, the electron orbiting device 140 is similar to the device 100 of FIG. 7. However, the obiting device '140 is provided with a light shield 150 which is disposed between the electron emitting filament 88 and the outer electrode 144 so as to minimize the photoelectric emission of electrons from the outer electrode 144 due to light from the filament 88. The illustrated light shield 150 is in the form of a cylindrical tubular electrode having a diameter less than that of the internal cylinder 146 but substantially greater than that of the axial rod electrode 148. The cylindrical shield 150 is received within the outer electrode 144 and around the central electrode 148. The shield electrode 150 may be connected to ground, so that it will be at the same potential as the grounded outer electrode 144. It will be understood, however, that a biasing voltage may be applied to the shield electrode '150, if desired. At the end adjacent the filament 88, the shield electrode "150 is stepped inwardly to form a shoulder 152 and a reduced internal cylindrical bore or surface 154. The filament 88 projects into the electron discharge device through the reduced bore 154. The ceramic tube 50, as illustrated in FIGS. 1-7 may be employed to insulate the lead-in wires for the filament 88 and may be disposed within the bore 154. It will be understood that the form of the insulator may be varied as desired. As in the case of the embodiments of FIGS. 1-9, the central electrode 148 may be supplied with a positive voltage, with respect to the outer electrode 144. The voltage may be derived from any suitable source such as the battery 32, corresponding to that of FIG. 1. The meter 36, for measuring the ion current, may also be connected between the outer electrode 144 and ground, as in the arrangement of FIG. 1. The reflecting electrode 122 of FIG. 8 may be mounted opposite the end of the outer electrode 144, remote from the filament 88.

Some or most of the electrons from the filament 88 go into spiral orbits around the central electrode 148. The electrons spiral along the inside of the shield electrode and then pass out of the shield electrode into the space between the outer electrode 144 and the central electrode 148. In this case, the shield electrode 150 is substantially shorter than the outer electrode 144 so that the shield electrode extends only part way along the outer electrode.

Inasmuch as the filament 88 is heated to an electron emitting temperature, the filament also gives off light. If the light is allowed to fall directly upon the outer electrode 144, the light causes photoelectric emission of electrons from the outer electrode. Such emission produces a current through the meter 36. Such current is combined with and tends to obscure the ion current produced by the movement of positively charged gasions to the outer electrode 144. However, in the embodiment of FIG. 11, the shield electrode 150 prevents the light from the filament 88 from falling directly upon the outer electrode 144. The light from the filamentv 88 must be reflected several times Within the light shield 150 before the light can reach the outer electrode 144. Of course, these reflections greatly reduce the amount of light which reaches the outer electrode from the filament. Thus, the photoelectric emission of electrons by the outer electrode is greatly reduced so that it becomes a virtually negligible factor. The provision of the light shield 1'50 increases the sensitivity and accuracy of the electron discharge device 140, particularly when employed as an ion gauge. The electron orbiting devices illustrated thus far are particularly useful as ion gauges to measure the concentration of gas molecules in a vacuum chamber or system. The orbiting devices are also useful for ionizing gas materials in ion-getter vacuum pumps. With suitable modification, the electron orbiting devices of the present invention will have many other applications. Thus, FIG. 12 illustrates a modified electron orbiting device which is arranged to provide an electrometer amplifying tube. The device may also be employed in connection with many other applications in which amplification is desired.

The electron orbiting device 160 is quite similar to the devices already described in that it comprises an outer electrode 162 having an internal cylindrical surface 164 within which a cylindrical inner electrode 166 is received. As before, the inner electrode 166 may be in the form of a cylindracl wire or rod extending along the axis of the internal cylinder 164. The electrodes 162 and 166 are mounted within a housing or enclosure 168 in which a vacuum is maintained. As before, a positive voltage is applied between the inner electrode 166 and the outer electrode 162. Such voltage may be derived from a battery 170 or any other suitable source. It has been found that a positive voltage of 200volts is suitable, but the voltage may be varied over a wide range.

The electron orbiting device 160 may employ the same electron injector 84 as illustrated in FIG. 6. A current to heat the filament 88 may be derived from any suitable source such as a battery 172. The filament 88 and the shield wire 86 may be given a positive bias derived from a battery 174 or any other suitable source. The reflector electrode 68 of FIG. 1 may also be employed and may be given a biasing voltage derived from a battery 176 or some other suitable source. In some cases, the voltage on the reflector 68 may be the same as the voltage on the outer electrode 162, in which case the reflector 68 is merely grounded.

As before, electrons from the filament 88 go into spiral orbits around the central electrode 166. The spiraling electrons travel along the space between the electrodes 162 and "164 and eventually pass out of the outer electrode 162 at the end thereof remote from the filament 88. In this case, a collector electrode 180 is disposed adjacent the remote end of the outer electrode 162. Such electrode is adapted to collect the spiraling electrons which pass out of the outer electrode 162. A positive voltage may be applied to the collector electrode so that the electrons will be attracted to such electrode. The positive voltage may be derived from the battery 170 or any other suitable source. A rneter 182 or any other suitable output device may be connected in circuit with the collector electrode 180. The meter 182 is adapted to measure the current to the collector electrode 180.

As illustrated, the collector electrode 180 is in the form of a flat circular disk disposed opposite the end of the outer electrode 162 and generally perpendicular to the axis of the inner electrode 166. The inner electrode 166 may pass through a central opening 184 in the collector electrode 180.

At a point disposed between the electron emitting filament 88 and the collector electrode 180, the electron discharge device 160 is provided with a control electrode 186 which regulates the passage of the electrons to the collector electrode. As shown, the control electrode 186 comprises a wire formed into an annular shape and mounted coaxially around the inner electrode 186 and within the outer electrode 162. A lead-in wire 188 extends to the control electrode 186' through an opening 190 in the outer electrode 162. The voltage or signal .to be measured or amplified is applied across input terminals 192 and 194. The input terminal 192 is connected to the control electrode 186 while the terminal 194 is grounded.

It has been found that the electron orbiting device 160 of FIG. 12 provides a sensitive amplifying device. Thus, any change in the voltage on the control electrode 186 changes the current to the collector electrode 180. Moreover, it has been found that the input impedance between the control electrode 186 and ground is extremely high, inasmuch as the control electrode draws substantially no current, particularly when the control electrode is maintained at a negative potential relative to the filament 88. By means of a suitable battery 196, the control electrode 186 may be biased negatively relative to the grounded outer electrode 162 but it is normally suflicient to return the input circuit to ground so that the control electrode 186 is maintained at the same bias potential as the outer electrode 162. It has been found that the input impedance of the electron orbiting device 160 is at least as high as that of other available electrometer tubes. Moreover, the electron discharge device 160 of the present invention gives a considerably higher gain than other available electrometer tubes. The higher gain is a distinct advantage, Whether the tube is employed as an electrometer tube or for other amplifying purposes.

FIG. 13 illustrates another modified amplifying tube 200 intended particularly for amplifying signals at ultrahigh frequencies. Here again, the device is mounted within a housing or envelope 202 in which a vacuum is maintained. In this case, the device 200 comprises an outer electrode 204 which may be in the form of a metal block or body through which a cylindrical bore 206 has been formed. The device 200 comprises an inner electrode 208 in the form of a cylindrical wire or rod extending axially within the bore 206.. To provide for eflicient use at ultrahigh frequencies, the bore 206 may be of small size, such as of an inch. The outer electrode 204 may be grounded. A positive voltage of 200 volts, or some other suitable voltage, may be applied between the axial electrode 208 and ground. Thus, the central electrode 1'0 208 is connected to a positive terminal 210 to which the power supply is connected. The negative power supply terminal 212 is grounded.

In this case, electrons are injected into the space between the outer and inner electrodes 204 and 208 by means of an electron emitting filament 214 disposed in such space. As shown, the filament 214 comprises a fine wire, made of tungsten or some other suitable material. One end of the filament wire 214 may be Welded or otherwise secured to the outer electrode 204, the Weld being indicated at 216. The filament 214 extends generally in the same direction as the inner electrode 208 but the filament angles inwardly toward the inner electrode from the weld point 216 at which the filament is secured to the outer electrode 204. The other end of the filament 214 is connected to a support in the form of a heavier lead-in wire 218. The filament 214 may be heated to an electron emitting temperature by passing current through the filament. Thus, the lead-in wire 218 may be connected to a power supply terminal 220, the other power supply terminal 222 being grounded.

As before, some of the electrons emitted by the filament 214 go into spiral orbits around the central electrode 208. It will be seen that the central electrode 208 extends out of the cylindrical bore 206 beyond the right-hand end of the outer electrode 204, as shown in FIG. 13. Some of the spiraling electrons pass out of the bore 206 and continue to spiral around the central electrode 208. A collector electrode 226 is disposed to the right of the outer electrode 204 and adjacent the central electrode 208. Thus, the collector electrode is spaced from the filament 214. At a point closer to the end of the outer electrode 204, the discharge device 200 is provided with a control electrode 228 which is illustrated as a ring disposed around the central electrode 208 and spaced from the outer electrode 204. The illustrated control electrode 228 is cylindrical in form and has an inner diameter corresponding to that of the bore 206 in the outer electrode 204. The current to the collector electrode 226 may be varied'by changing the voltage on the control electrode 228. Thus, the signal to be amplified is applied between the control electrode 228 and the grounded outer electrode 204. Accordingly, FIG. 13 illustrates input terminals 230 and 232 connected to the control electrode 228 and to the outer electrode 204, respectively.

A positive voltage is applied to the collector electrode 226 so that it will attract electrons. Thus, the collector electrode 226 is connected to a positive power supply terminal 236 through an output device 238. The negative power supply terminal 240 is grounded.

Due to the small size of the electron orbiting device 200 of FIG. 13, the device functions efliciently as an amplifier at ultrahigh frequencies. The coaxial arrangement of the electron discharge device also contributes to the efiiciency and utility of the device at ultrahigh frequencres.

It will be apparent that the electron orbiting devices of the present invention have many advantages and applicatrons. Thus, for example, they find important applications as 1011 gauges, ionizing devices for ion-getter vacuum pumps, electrometer tubes and high frequency amplifying devices. An important factor in the operation of the electron orbiting devices is the manner in which the electrons are caused to move in spiral orbits between the cylindrical electrodes. Such orbital movement of the electrons is achieved without providing any magneticfield to deflect the electrons. The orbital movement of the electrons is caused by the character of the electric field between the electrodes and the manner in which the electrons are injected into the space between the electrodes.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention as exemplified in the foregoing description and defined in the following claims.

' We claim:

1. An electronic device,

comprising the combination of a hollow generally cylindrical boundary electrode,

envelope means forming a vacuum space including the interior of said boundary electrode,

a cylindrical anode extending axially within said boundary electrode,

said boundary electrode being spaced outwardly from said anode,

means for injecting electrons into the space between said anode and said boundary electrode at a predetermined injection point therebetween with substantial angular momentum about said anode so that the electrons will travel in spiral orbits around said anode,

a collector anode spaced along said cylindrical anode from said injection point for collecting the spiralling electrons,

and a control electrode disposed between said injection point and said collector anode for controlling the movement of the spiralling electrons to said collector anode.

2. A device according to claim 1,

in which said control electrode comprises a ring-shaped member extending around said cylindrical anode and spaced outwardly therefrom.

3. A device according to claim 1,

comprising means for producing a positive voltage on said collector anode relative to said boundary electrode so as to attract the spiralling electrons.

4. A device according to claim 1,

in which said collector anode is in the form of an annular member extending around and spaced outwardly from said cylindrical anode.

5. A device according to claim 1,

in'which said cylindrical anode has an end portion which extends outwardly from said boundary electrode beyond the corresponding end thereof,

and in which said collector anode is disposed along said outwardly extending end portion of said cylindrical anode.

6. A device according to claim 1,

in which said cylindrical anode has an end portion which extends outwardly from said boundary electrode beyond the corresponding end thereof,

and in which said collector anode and said control electrode are disposed along said outwardly extending end portion of said cylindrical anode.

7. A device according to claim 1,

in which said means for injecting electrons comprises an electron emitting cathode disposed in the space between said cylindrical anode and said boundary electrode.

8. A device according to claim 1,

in which said means for injecting electrons comprises an electron emitting thermionic cathode disposed in the space between said cylindrical anode and said boundary electrode.

9. An electronic device,

comprising thecombination of a hollow generally cylindrical boundary electrode,

envelope means forming a vacuum space including the interior of said boundary electrode,

a cylindrical anode extending axially within said boundary electrode,

said boundary electrode being spaced outwardly from said anode,

means for injecting electrons into the space between said anode and said boundary electrode at a predetermined injection point therebetween with substantial angular momentum about said anode so that the electrons will travel in spiral orbits around said anode,

a collector anode spaced along said cylindricalanode from said injectionpoint for collecting the spiralling electrons,

and a control electrode disposed between said injection point and said collector anode for controlling the movement of the spiralling electrons to said collector anode,

said means for injecting electrons comprising an elongated electron emitting cathode disposed in the space between said cylindrical anode and said boundary electrode and generally parallel to said cylindrical anode, and an elongated shield electrode positioned between said electron emitting cathode and said cylindrical anode for modifying the electric field therebetween whereby the electrons emitted by said cathode are given sufficient angular momentum to go into orbits around said cylindrical anode.

10. A device according to claim 9,

in which said cathode comprises a thermionic filament.

11. A device according to claim 9,

in which said cathode comprises a thermionic filament having one end connected to and supported by the corresponding end of said shield electrode.

12. A device according to claim 9,

in which said cathode comprises a thermionic filament in the form of a fiat loop of wire disposed generally in a radial plane which includes the axis of said cylindrical anode.

13. A device according to claim 9,

comprising means for producing a positive voltage on said cylindrical anode relative to said boundary electrode.

14. A device according to claim-13,

comprising means for producing a positive biasing voltage on said cathode and said shield electrode relative to said boundary electrode,

said positive biasing voltage being substantially less than the positive voltage on said cylindrical anode.

15. An electronic device,

comprising the combination of a hollow generally cylindrical boundary electrode,

envelope means forming a vacuum space including the interior of said boundary electrode,

a cylindrical anode extending axially within said boundary electrode,

said boundary electrode being spaced outwardly from said anode,

means for producing a positive voltage on said anode relative to said boundary electrode,

an electron emitting cathode in the form of a thermionic filament disposed between said anode and said boundary electrode and substantially parallel to said anode,

a shield wire adjacent said filament and substantially parallel thereto,

said shield wire being positioned between said filament and said anode for preventing direct movement of electrons therebetween whereby the electrons emitted by said filament will be injected into spiral orbits around said anode,

means for producing a positive biasing voltage on said filament and said shield electrode relative to said boundary electrode,

said positive biasing voltage being substantially less than the positive voltage on said anode,

a collector anode spaced along said cylindrical anode from said filament for collecting the spiralling electrons,

means for producing a positive voltage on said collector anode relative to said boundary electrode for attracting the spiralling electrons,

and a control electrode disposed between said filament and said collector anode for controlling the movement of the spiralling electrons to said collector anode.

16. A device according to claim 15,

in which said collector anode comprises an annular member extending around and spaced outwardly from in which said cylindrical anode has an outwardly prosaid cylindrical anode. jecting end portion which extends outwardly from 17. Adevice according to claim 15, said boundary electrode beyond the corresponding in which said control electrode comprises a ring memend thereof,

ber extending around and spaced outwardly from said 5 and in which said collector anode and said control eleccylindrical anode. trode are disposed along said outwardly projecting 18. A device according to claim 15, end portion of said cylindrical anode. in which said cylindrical anode has an outwardly projecting end portion which extends outwardly from References Cited y the Examine! said boundary electrode beyond the corresponding 10 UNITED STATES PATENTS f F 2,131,896 10/1938 Malter 230-69 and m WhlCh sa1d collector anode 1s dlsposed along sa1d 3,051,868 8/1962 Redhead 324 33 X outwardly projecting end portion of said cylindrical 3 11 77 1 9 4 Gabor anode. A device according o claim 1 15 GEORGE N. WESTBY, Primary Examiner.

C. R. CAMPBELL, Assistant Examiner. 

1. AN ELECTRONIC DEVICE, COMPRISING THE COMBINATION OF A HOLLOW GENERALLY CYLINDRICAL BOUNDARY ELECTRODE, ENVELOPE MEANS FORMING A VACUUM SPACE INCLUDING THE INTERIOR OF SAID BOUNDARY ELECTRODE, A CYLINDRICAL ANODE EXTENDING AXIALLY WITHIN SAID BOUNDARY ELECTRODE, SAID BOUNDARY ELECTRODE BEING SPACED OUTWARDLY FROM SAID ANODE, MEANS FOR INJECTING ELECTRONS INTO THE SPACE BETWEEN SAID ANODE AND SAID BOUNDARY ELECTRODE AT A PREDETERMINED INJECTION POINT THEREBETWEEN WITH SUBSTANTIAL ANGULAR MOMENTUM ABOUT SAID ANODE SO THAT THE ELECTRONS WILL TRAVEL IN SPIRAL ORBITS AROUND SAID ANODE, A COLLECTOR ANODE SPACED ALONG SAID CYLINDRICAL ANODE FROM SAID INJECTION POINT FOR COLLECTING THE SPIRALLING ELECTRONS, AND A CONTROL ELECTRODE DISPOSED BETWEEN SAID INJECTION POINT AND SAID COLLECTOR ANODE FOR CONTROLLING THE MOVEMENT OF THE SPIRALLING ELECTRONS TO SAID COLLECTOR ANODE. 